Method _preview_thread

editor/audio/audio_stream_preview.cpp:119–179

}

void AudioStreamPreviewGenerator::_preview_thread(void *p_preview) {
	Thread::set_name("AudioStreamPreviewGenerator");

	Preview *preview = static_cast<Preview *>(p_preview);

	float muxbuff_chunk_s = 0.25;

	int mixbuff_chunk_frames = AudioServer::get_singleton()->get_mix_rate() * muxbuff_chunk_s;

	Vector<AudioFrame> mix_chunk;
	mix_chunk.resize(mixbuff_chunk_frames);

	int frames_total = AudioServer::get_singleton()->get_mix_rate() * preview->preview->length;
	int frames_todo = frames_total;

	preview->playback->start();

	while (frames_todo) {
		int ofs_write = uint64_t(frames_total - frames_todo) * uint64_t(preview->preview->preview.size() / 2) / uint64_t(frames_total);
		int to_read = MIN(frames_todo, mixbuff_chunk_frames);
		int to_write = uint64_t(to_read) * uint64_t(preview->preview->preview.size() / 2) / uint64_t(frames_total);
		to_write = MIN(to_write, (preview->preview->preview.size() / 2) - ofs_write);

		preview->playback->mix(mix_chunk.ptrw(), 1.0, to_read);

		for (int i = 0; i < to_write; i++) {
			float max = -1000;
			float min = 1000;
			int from = uint64_t(i) * to_read / to_write;
			int to = (uint64_t(i) + 1) * to_read / to_write;
			to = MIN(to, to_read);
			from = MIN(from, to_read - 1);
			if (to == from) {
				to = from + 1;
			}

			for (int j = from; j < to; j++) {
				max = MAX(max, mix_chunk[j].left);
				max = MAX(max, mix_chunk[j].right);

				min = MIN(min, mix_chunk[j].left);
				min = MIN(min, mix_chunk[j].right);
			}

			uint8_t pfrom = CLAMP((min * 0.5 + 0.5) * 255, 0, 255);
			uint8_t pto = CLAMP((max * 0.5 + 0.5) * 255, 0, 255);

			preview->preview->preview.write[(ofs_write + i) * 2 + 0] = pfrom;
			preview->preview->preview.write[(ofs_write + i) * 2 + 1] = pto;
		}

		frames_todo -= to_read;
		callable_mp(singleton, &AudioStreamPreviewGenerator::_update_emit).call_deferred(preview->id);
	}

	preview->preview->version++;

	preview->playback->stop();